Another aspect of avoidance is putting in place protections for important river corridors to ensure maintenance of connectivity over the long term. The Albanian government has recently taken steps to protect the Vjosa River, rare in Europe due to how it retains its natural flow dynamics, including sediment flows and floodplains. Work is already underway to upgrade the protection level of the Vjosa River Basin and its free-flowing tributaries to an IUCN Category II Level National Park with the river corridor itself to be protectedvi.
Where new infrastructure such as culverts, levees, and dams is deemed necessary, siting, structure design and operation will be critically important for minimizing impacts. For example, the addition of a passage facility at the site of the Pak Peung wetland along the Mekong River in Laos, where irrigation infrastructure has been blocking the movement of species into the wetland, allowed passage of 100 fish species and fish catch became greater in the late wet season as compared to a no-fish pass control sitevii.
Reconnecting freshwater systems that have already been fragmented can lead to quick improvements to the health of and benefits from aquatic ecosystems. In locations where infrastructure has been removed and species are still present, recovery can be dramatic. One such example comes from the River Villestrup in Denmark. Six weirs were removed and the brown trout smolt run went from 1,600 to about 19,000 from 2004 to 2015 and the spawning population from 350 to 3,600viii. Thus, restoration is critically important to bending the biodiversity curve where fragmentation has hammered freshwater species populations.
Restoring floodplains and recharging groundwater sources are also critical for flood control and water supply, especially in an era of increasing floods and water scarcity. In Thailand, the Ing River floodplain stores and conveys floodwaters and was credited with sparing a neighboring village from inundation during a major flood in 2010ix.
We have the tools to act now. First, avoiding barriers in the most harmful locations and/or via protections for critically important freshwater connectivity corridors. Second, mitigating impacts where barriers are inevitable via barrier design or dam re-operation for environmental flows. And third, restoring rivers, floodplains, and the recharge of groundwater.
With the recent launch of the country-led Freshwater Challenge aiming to restore and conserve 865 million acres of wetlands and 186,411 miles of rivers globally and with the explicit inclusion of “inland waters” in the targets of the new global biodiversity agreementx, the moment is now to take these steps. We are risking further degradation of our rivers and the life they support, including the majestic species migrations that drive our imagination. Our imagination should know no bounds, neither should our ambition or our commitment to act.
